A conventional transmitting apparatus operative at a plurality of different bands commonly adopts an offset phase-lock-loop (OPLL) as a substitute for a surface acoustic wave (SAW) filter to reduce noise interference. However, in order to allow the transmitting apparatus to operate at different bands, a frequency divider in a conventional OPLL is required to adopt different divisors corresponding to the different bands. Such an approach of utilizing different divisors for accommodating the different bands not only makes design of an overall circuit of the conventional transmitting apparatus more challenging, but also significantly increases production costs. For example, when a divisor utilized by a frequency divider changes along with different bands at which the transmitting apparatus operates, other related circuits, e.g., an offset mixer and a filter in the OPLL, also need to be operative under the different bands. As a result, the design of the overall circuit inevitably becomes more challenging. Further, since the divisor in the frequency divider varies the intermediate frequency, several additional analog baseband circuits are needed for processing associated signals.